The inventor of this invention often travels around the world for international trade, and frequently troubled by time difference between countries or areas. At that time, the difficulties and complicate for finding the exact time are always discouraged people. Now for the better understanding, we make a comparison among the main exsisting types of world clocks.
I Circular display type such as disclosed in U.S. Pat. Nos. 4,579,460 and 5,146,346, the primary design is to print the world map of North or South Pole projection with respecting to the right time and the right cities.
The drawbacks comprise:
1. Spherical projection is not as easy as cylindric projection;
2. People are not accustomed to the radical arrangement for the main cities, if compare the horizontal or vertical arrangement;
3. The cost is high for its complicate structure.
II Data-Bank type such as disclosed in U.S. Pat. No. 5,448,532, whose main design is to built in a data bank of each respective regional time to the product for users to check by pushing button. Although this type is more compact and however, the operation process is repeated and complicate, and is not available f or displaying the exact time synchronously. In addition, the cities for reference are quite limited. Therefore, this type is not excellent, either.
III Type for reference between electronics and map such as disclosed in U.S. Pat. No. 4,779,247, U.S. Pat. No. Des 312,788, and U.S. Pat. No. Des 312,971, whose design basically is a combination of data-bank and world concise map. Similarly, operations required, and unable to be displayed regional time synchronously, are the main drawbacks.
IV Globe type such as disclosed in U.S. Pat. No. 4,477,193 and U.S. Pat. No. 5057024, both patents are related to the application of globe. The former one is joined with electronic clock of displaying regional time; the latter is combined with personal computer. Consequently, they are complicate and high cost. However, they also can not display the exact regional time synchronously.
V Digital type such as disclosed in U.S. Pat. No. 3,918,251, this design concept is close to this invention. It move one box per hour carried by the closed belt and the machine power of digital clock, to display the hour of 24 regional time, and to show the minute by a 2-digital drum, and to set the minute display zero as the standard time for driving the belt. Because the said us patent does not provide drawings for reference, the detail invention is still unknown. However, since the belt is carried by the machine power of digital clock, and the extra load for carrying belt is not fully considered in original digital clock design, the punctual degree will be influenced, and results in stop moving lastly. During my research, I already found that even the driving of small belt also need a relative power and torque. This reveals that there are always certain difference between theory and practice.
From above discussion, we known that the existing world clocks are somewhat inconvenience for users. This is also the motive for me to create this invention.